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Employee Benefit Plans (AOCI ) (Details) - CAD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Pension Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Actuarial losses | $ (246) | $ (251)
Past service (gains) | (2) | (3)
Regulatory Assets | 389 | 315
Accumulated Other Comprehensive Income (Loss), before Tax, Total | 633 | 563
Deferred Tax Assets, Defined Benefit Plan | (5) | (2)
Net amount in AOCI after tax adjustment | 628 | 561
Non-pension Benefit Plans [Member |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Actuarial losses | 7 | 4
Past service (gains) | 0 | 0
Regulatory Assets | 65 | 78
Accumulated Other Comprehensive Income (Loss), before Tax, Total | 58 | 74
Deferred Tax Assets, Defined Benefit Plan | 2 | 0
Net amount in AOCI after tax adjustment | $ 60 | $ 74

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